Alkynylbis(alkylidynyl)phosphines: {LnMC}2PCCR

Abstract

Sequential treatment of [M(CBr)(CO)₂(Tp*)] (M = Mo, W; Tp* = hydrotris(dimethylpyrazolyl)borate) with ⁿBuLi, RPCl₂ and LiCCSiMe₃ affords [M{CPR(CCSiMe₃)}(CO)₂(Tp*)] (R = Ph, Cy) which are readily desilylated (TBAF) to provide the parent ethynyl derivatives [M{CPR(CCH)}(CO)₂(Tp*)]. Alternatively, treating [W(CBr)(CO)₂(Tp*)] with ⁿBuLi, 1/2 PCl₃ and LiCCR′ affords the alkynylbis(alkylidynyl)phosphines [R′CCP{CW(CO)₂(Tp*)}₂] (R′ = C₆H₅, C₆H₄Me-4, CMe₃, SiMe₃) and again the silyl derivative may be desilylated to the parent (R′ = H) which is readily converted to an arsino derivative (R′ = AsPh₂). These novel architectures present new linkages for bridge-assisted polymetallic assembly.